The invention relates to a trailer coupling for a motor vehicle for attaching a trailer or supporting a load carrier, with a coupling arm provided with a coupling element for coupling-on the trailer or load carrier, and at least one sensor mounted on the coupling arm for detecting a deformation of the coupling arm due to a load acting on the coupling arm.
For detecting loads acting on a trailer coupling, it has been known for some time, from DE 10 2012 021 352 A1 amongst others, to affix for example strain gauges to the body of the coupling arm. If the coupling arm is stretched or compressed, the affixed strain gauge is likewise deformed with it, leading to the sensor (strain gauge) emitting a signal representing the deformation. With the aid of this measuring signal, a nose weight or a tensile load may be determined.
If such a sensor no longer functions, for example because it is damaged, it must be removed, which is time-consuming, and replaced by another sensor. A fresh calibration then begins, so that the measured results supplied by the sensor are accurate.